Field of the Invention
The present invention relates to wireless communications, and more particularly to a device-to-device (D2D) communication method and apparatus based on channel hopping.
Related Art
In most traditional communication environments, users access a server through user devices to download or upload desired content. Such a server-based communication environment is referred to as an infrastructure communication environment. In the infrastructure communication environment, users generally access a server through a base station (BS) of cellular communication or an access point (AP) of a wireless local area network (WLAN).
Recently, device-to-device (D2D) communication receives growing attention. A large number of smartphone applications support D2D communication-based services. D2D communication supports direct communication between user devices. So far, D2D communication has been supported mostly in an application layer. When D2D communication is supported only in the application layer, a server still serves as a relay to connect user devices and user devices may operate in a physical (PHY) layer and a medium access control (MAC) layer in the same way as in the infrastructure communication environment.
When D2D communication is supported also in a PHY layer and MAC layer of a user device, data transmission and/or reception may be performed directly between user devices via no server in D2D communication, unlike in the infrastructure communication environment. That is, data for D2D communication may be transmitted directly between user devices via no server, thereby efficiently using communication resources.
When D2D communication is supported also in a PHY layer and MAC layer of a user device, a transmission delay is reduced and transmission is performed within a relatively close range, and thus transmission power may be also saved. In addition, since no connection is necessary between a user device and a server, a user may transmit massive data to another user device without charge.
In the D2D communication environment, communication between user devices is performed via no BS or AP, and thus it is necessary to design a PHY layer and MAC layer for D2D communication in view of resource allocation, interference avoidance, and synchronization.